Distribution and Energies of Grain Boundaries in Magnesia as a Function of Five Degrees of Freedom

Authors

  • David M. Saylor,

    1. Materials Science and Engineering Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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    • *

      Member, American Ceramic Society.

    • Current address: National Institute of Standards and Technology, Gaithersburg, Maryland.

  • Adam Morawiec,

    1. Materials Science and Engineering Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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    • Instytut Metalurgii i Inzynierii Materialowej PAN, Reymonta 25, 30–059 Krakow, Poland.

  • Gregory S. Rohrer

    1. Materials Science and Engineering Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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    • *

      Member, American Ceramic Society.


  • D. Wolf—contributing editor

  • This work was supported primarily by the MRSEC program of the National Science Foundation under Award Number DMR-0079996.

Abstract

The multiplicity of distinct grain boundary configurations in polycrystals has made it difficult to determine the relative frequency with which each configuration is adopted. As a result, the physiochemical properties of each boundary and the influence of the distribution of boundaries on macroscopic materials properties are not well understood. Using a semiautomated system, we have measured all five macroscopically observable degrees of freedom of 4.1 × 106 boundary plane segments making up 5.2 × 106μm2 of grain boundary interface area in a magnesia polycrystal. Our observations demonstrate that not all grain boundary configurations occur with the same frequency and that the relative free energies of the different interfacial configurations influence the population distribution. Furthermore, the results indicate that relative grain boundary energies can be estimated based on the free surface energies.

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